Before reading the regeneration details for this crop, read the general introduction that gives general guidelines to follow by clicking here.

Introduction

Pigeonpea (Cajanus cajan (L.) Millsp., syn. Cajanus indicus) is a member of the Fabaceae family and has many wild relatives. These include Cajanus scarabaeoides (L.) Thouars, C. sericeus (Benth. ex Baker) Maesen, C. acutifolius (F. Muell.) Maesen, C. albicans (Wight & Arn.) Maesen, Rhynchosia aurea, R. bracteata Benth. ex Bak and Flemingia bracteata (Roxb.) Wight (van der Maesen 1985). The pigeonpea plant is an erect annual or short-lived perennial reaching a height of 1–3 m. Because the coarse bush is deeply rooted, it has wide adaptability and grows well in semi-arid areas. It has slender, pointed trifoliate leaves and yellow or yellow and red flowers. Pods are green and pointed with some reddish mottling. Several pods are produced in clusters on an upright stem.
Pigeonpea is often cross-pollinated by bees (Megachile spp.). Cross-pollination ranges from 0–40% depending on genotype and insect pollinator populations (van der Maesen 1985). Consequently, precautions are needed during regeneration to preclude cross-pollination and preserve the genetic integrity of germplasm accessions.

Pigeonpea is a short-day species which flowers early with short days. Day length of 11–11.5 hours (Gooding 1962) and a temperature range of 22–30°C (Whiteman et al.1985) are suitable for crop growth.

Preparation for regeneration

Time to regenerate

When seed stocks are <50 g.

When germination drops to below 75%.

When more than 25% of seeds are infected by one or more fungi, such as Alternaria, Aspergillus, Cladosporium, Curvularia, Fusarium, Macrophomina, Penicillium, Phoma and Rhizopus spp. (Rao and Bramel 2000).

Seed sample

To maintain genetic integrity, use a seed sample from the original source whenever possible.

The minimum number of plants required for regeneration is 180.

About 23 g of seed are required to regenerate an accession.

Treat the seed with an effective fungicide to control seed-borne fungi.

For each accession, prepare one seed packet for planting each row.

Label the packets with identification number and row number and arrange them according to field lay-out.

Field selection and preparation

Choose a field that has not been under pigeonpea for the previous 2 years to reduce disease risk.

Fill small plastic/paper cups or small pots (10 x 10 cm with a hole in the bottom) with a pasteurized mixture of 3 parts soil to 1 part farmyard manure.

Scarify the seeds by making a small cut in the seed coat to improve water absorption and germination.

Dress the seeds with fungicide to control seed-borne diseases.

Put two to four seeds in each pot at about 3 cm depth.

Water the pots every day using watering cans (Rao and Bramel 2000).

Transplanting

Use large pots (30 x 30 cm) filled with a pasteurized mixture of soil and farmyard manure (3:1) for creeping herbs such as C. platycarpus, C. scarabaeoides and Rhyncosia species. Plant out perennial shrubs and creepers such as C. albicans, C. crassus, C. goensis, C. heynei and C. mollis in a field genebank.

Transplant seedlings when they have three or four leaves or are 2–5 cm tall.

Transplant the seedling to the appropriate pot or field in the evening and water it.

Keep the new pots in shade for 2 days, keeping the soil moist.

If transplanted to the field, plant in rows 4 m long with a spacing of at least 25 cm between plants and arrange shade for 2 days.